246 OBSERVATIONS ON THE NATURE OF HEAT. 
the laws of motion. For instance, whenever a moving force is ap- 
plied to any body at rest, part of that force is expended in overcom- 
ing the inertia of matter; consequently, the power is less efficient 
than when the inertia has been overcome. These facts, however, 
by no means coincide with Berthollet’s experiments with the metals, 
as specified. The first blow, having to overcome the actual or com- 
parative inertia of matter, would naturally, on this view, afford least 
caloric, as the motion among the particles would be less than on the 
succeeding blows ; but the reverse was the fact, as the first blow af- 
forded the greatest quantity of caloric. That caloric already existing 
in bodies is merely evolved on percussion or friction, is an assumption 
as destitute of proof as that which Dr. Young has assumed ; but it 
does not violate any of the known laws of matter, or rather it coim- 
cides with some of those laws which the opposite idea directly sets at 
nought. Therefore, it is certainly more logical to adopt that opinion 
which is supported by reasons, though not stronger than analogy, in 
preference to another not only destitute of analogical reasoning, but 
running directly counter to what analogy might lead us to expect. 
The same author remarks that “those who look up with unquali- 
fied reverence to the dogmas of the modern schools of chemistry, will 
probably long retain a partiality for the convenient, but superficial 
and inaccurate, modes of reasoning which have been founded on the 
favourite hypothesis of the existence of caloric as a separate substance ; 
but it may be presumed that, in the end, a careful examination of 
the facts which have been adduced in confutation of that system will 
make a sufficient impression on the minds of the cultivators of che- 
mistry to induce them to listen to a less objectionable theory.” Not- 
withstanding the denunciation of being a superficial and imaccurate 
reasoner, I am induced, after taking a retrospect of all the facts con- 
nected with caloric, to consider it material. This view gives the most 
satisfactory explanation of the greater part of the phenomena depen- 
dent upon caloric, though a few of them, as instanced in the case of 
bodies becoming larger and at the same time emitting caloric, may at 
first stagger us in this belief, yet if we deal with the subject as is 
done with the other objects of nature, there can be no hesitation about 
the conclusion I have drawn: I allude to the formation ofa law from 
the general effect of any body, rather than from the exceptions to it. 
The invention of the hypothesis that caloric depends on motion, is 
ascribed to Lord Bacon ; and it is supported by the opinions both of 
Boyle and Newton. The opinion of such men ought certainly to 
